JP7262273B2 - Foamed particles and foamed moldings - Google Patents

Description

TECHNICAL FIELD The present invention relates to foamed particles and foamed moldings. More specifically, the present invention relates to a foamed molded article having a good appearance and high mechanical strength, which uses a polycarbonate-based resin as a base resin, and expanded particles that give this foamed molded article with good moldability.

Foam molded products are light, easy to process, have good shape retention, and have relatively high strength. ing. When heat resistance is not particularly required, polystyrene resin foam moldings are used, and when cushioning properties, recovery properties, flexibility, etc. are required, olefin resin foam moldings such as polypropylene and polyethylene are used. tend to be used.
As a resin generally having higher heat resistance than these polystyrene-based resins and olefin-based resins, there is a polycarbonate-based resin. This is a resin material that can be used even in harsh climates such as arid regions and tropical regions. This polycarbonate-based resin is not only excellent in heat resistance, but also excellent in water resistance, electrical properties, mechanical strength, aging resistance and chemical resistance. For this reason, polycarbonate resins have hitherto been used as interior materials for buildings, but in recent years, their excellent properties have been used to expand their application to automotive components, packaging materials, various containers, and the like.

By the way, as a method for producing a foam molded product of a polycarbonate resin, for example, an in-mold foam molding method is known in which foamed particles are foamed and fused in a mold. In this method, a mold having a space corresponding to a desired shape is prepared, foamed particles are filled in the space, and the foamed particles are expanded and fused by heating to obtain a foamed molded article having a complicated shape. can be obtained. However, this method has the problem that the appearance of the foamed molded product is not good and the fusion between the foamed particles is not sufficient.
Therefore, the applicant of the present application has proposed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-188321) a technique for providing a foamed molded article with a good appearance by improving the fusion between foamed particles.

JP 2016-188321 A

In Patent Document 1, a foamed molded article with a good appearance is obtained, but by further improving the fusion between foamed particles, a foamed molded article with a better appearance and higher mechanical strength is provided. was desired.

In view of the above problems, the inventors of the present invention made it possible to improve the appearance and mechanical strength of a foamed molded product obtained from expanded beads by setting the volume multiple and the average cell diameter of the expanded beads to specific ranges. At the same time, the inventors have unexpectedly found that the mutual fusion between foamed particles can be improved, resulting in the present invention.
Thus, according to the present invention, a foamed particle having a polycarbonate-based resin as a base resin,
The expanded beads have a value within the range of 2.5 to 12 μm/times when the average cell diameter of the expanded beads is divided by the bulk multiple of the expanded beads.

Further, according to the present invention, a foamed molded article made of a polycarbonate-based resin as a base resin and composed of a plurality of foamed particles,
The foam molded article has a value within the range of 2.5 to 12 μm/times when the average cell diameter of the foam molded body is divided by the multiple of the foam molded article. be done.

According to the present invention, a foamed molded article having a good appearance and mechanical strength and improved fusion bondability using a polycarbonate resin as a base resin, and a polycarbonate resin foamed to give this foamed molded article with good moldability. Particles can be provided.
In any of the following cases, a foamed molded article having better appearance and mechanical strength and improved fusion bondability using a polycarbonate resin as a base resin, and a polycarbonate system that provides this foamed molded article with good moldability. Foamed particles of resin can be provided.
(1) The expanded beads exhibit a bubble number density of 1.0×10 ⁷ to 1.0×10 ⁹ /cm ³ .
(2) The expanded particles have a bulk multiple of 2 to 20 times.
(3) The expanded particles have an open cell rate of 0-10%.

1 is photographs of cut surfaces of foamed particles and foamed moldings of Examples 1 to 6. FIG. Fig. 10 is a photograph of cut surfaces of foamed particles and foamed moldings of Examples 7 to 9; 1 is photographs of cut surfaces of foamed particles and foamed articles of Comparative Examples 1 to 3. FIG.

1. Expanded beads Polycarbonate-based resin is used as a base resin for expanded beads. In addition, the expanded beads show a value within the range of 2.5 to 12 μm/fold when the average cell diameter of the expanded beads is divided by the bulk multiple of the expanded beads. The inventors have found that by adjusting the bulk multiple and the average cell diameter, it is possible to further improve the appearance and fusion bondability of the foam molded product.

1-1. Value obtained by dividing the average cell diameter of the expanded beads by the volume multiple of the expanded beads The value obtained by dividing the average cell diameter of the expanded beads by the volume multiple of the expanded beads is within the range of 2.5 to 12 μm/times. If the value is less than 2.5 μm/fold, the cell membrane becomes thin and breaks during molding, the ratio of open cells increases, and the foamed particles may shrink due to buckling of the cells. If it is more than 12 μm/fold, the foam film may become thick and the formability may deteriorate. The value is preferably 3.0 to 10.0 μm/times, more preferably 3.0 to 6.5 μm/times.
The bulk multiple is preferably in the range of 2 to 20 times. If the bulk multiple is less than 2 times, the foam film may become thick and the formability may deteriorate. If it is more than 20 times, the cell membrane becomes thin and breaks during molding, the proportion of open cells increases, and the buckling of the cells may cause shrinkage of the foamed particles. The bulk multiple is more preferably 3 to 18 times, even more preferably 5 to 16 times.
The average cell diameter is preferably in the range of 20-200 μm. If the average cell diameter is less than 20 μm, the cell membrane becomes thin and may be broken during molding, the ratio of open cells increases, and shrinkage of expanded particles may occur due to buckling of cells. If the thickness is larger than 200 μm, the foam film may become thick and the formability may deteriorate. The average cell diameter is more preferably 20-150 μm, even more preferably 30-120 μm.

1-2. Bubble Number Density The bubble number density is preferably 1.0×10 ⁷ to 1.0×10 ⁹ /cm ³ . If the bubble number density is less than 1.0×10 ⁷ /cm ³ , it may be difficult to increase the density. When the cell number density is 1.0×10 ⁹ cells/cm ³ or more, the cell wall thickness becomes small and moldability may deteriorate. More preferably, the bubble number density is 3.0×10 ⁷ to 5.0×10 ⁸ /cm ³ .
Here, the bubble number density is given by the following formula:
Bubble number density = (ρ/D−1)/{(4/3)·π·(C/10000/2) ³ }
It can be calculated by In the formula, C is the average cell diameter (mm), ρ is the density of the polycarbonate resin (kg/m ³ ), and D is the apparent density of the expanded beads (kg/m ³ ).

The average cell diameter C is preferably in the range of 20 to 200 μm.
The density ρ of the polycarbonate-based resin is preferably in the range of 1.0×10 ³ to 1.4×10 ³ kg/m ³ . If the density ρ is less than 1.0×10 ³ kg/m ³ , the heat resistance temperature may decrease. If it is more than 1.4×10 ³ kg/m ³ , the heat resistant temperature may rise and foam molding may become difficult. Density ρ is more preferably 1.10×10 ³ to 1.35×10 ³ kg/m ³ , still more preferably 1.15×10 ³ to 1.30×10 ³ kg/m ³ .
The apparent density D of the expanded particles is preferably in the range of 20-640 kg/m ³ . If the apparent density D is less than 20 kg/m ³ , the cell membrane becomes thin and breaks during molding, the proportion of open cells increases, and the buckling of the cells may cause shrinkage of the foamed particles. If it is more than 640 kg/m ³ , the foam film may become thick and the formability may deteriorate. The apparent density D is more preferably 40-400 kg/m ³ , still more preferably 50-250 kg/m ³ .
Cell wall thickness is preferably in the range of 1 to 15 μm. When the average cell wall thickness is less than 1 μm, moldability, particularly fusion bonding, may deteriorate during molding. If it is larger than 15 μm, it may become difficult to increase the magnification. More preferably, the average cell wall thickness is 1 to 10 μm, and even more preferably 1 to 5 μm.

1-3. Open-cell rate The open-cell rate is preferably 0 to 10%. When the open cell ratio is more than 10%, the moldability of the foamed molded article may be deteriorated. More preferably, the open cell rate is 0 to 5%.

1-4. Polycarbonate-based resin The polycarbonate-based resin may be a straight-chain polycarbonate-based resin or a branched-chain polycarbonate-based resin.
The polycarbonate-based resin preferably has a polyester structure of carbonic acid and glycol or dihydric phenol. From the viewpoint of further improving heat resistance, the polycarbonate-based resin preferably has an aromatic skeleton. Specific examples of polycarbonate resins include 2,2-bis(4-oxyphenyl)propane, 2,2-bis(4-oxyphenyl)butane, 1,1-bis(4-oxyphenyl)cyclohexane, 1, Examples thereof include polycarbonate resins derived from bisphenols such as 1-bis(4-oxyphenyl)butane, 1,1-bis(4-oxyphenyl)isobutane, 1,1-bis(4-oxyphenyl)ethane and the like.
The polycarbonate-based resin may contain other resins than the polycarbonate resin. Other resins include acrylic resins, saturated polyester resins, ABS resins, polystyrene resins, polyolefin resins, polyphenylene oxide resins, and the like. The polycarbonate-based resin preferably contains 50% by weight or more of the polycarbonate resin.
Also, the polycarbonate resin preferably has an MFR of 1 to 20 g/10 min. Resins within this range are suitable for foaming, and can be easily foamed to a higher degree. A more preferred range of MFR is 2 to 15 g/10 min.

1-5. Shape of Expanded Beads The shape of the expanded beads is not particularly limited. For example, a spherical shape, a cylindrical shape, and the like can be mentioned. Among these, it is preferable that the shape is as close to spherical as possible. That is, it is preferable that the ratio of the minor axis to the major axis of the expanded beads is as close to 1 as possible.
The expanded particles preferably have an average particle size of 1 to 20 mm.

1-6. Method for Producing Expanded Beads Expanded beads can be obtained by impregnating resin particles with a foaming agent to obtain expandable particles and expanding the expandable particles.
1-6-1. Production of Expandable Particles Expandable particles can be obtained by impregnating resin particles made of polycarbonate-based resin with a foaming agent.
Resin particles can be obtained by a known method. For example, a polycarbonate-based resin, optionally with other additives, is melt-kneaded in an extruder and extruded to obtain strands, and the resulting strands are cut in air, cut in water, and heated. A method of granulating by cutting is exemplified. Commercially available resin particles may be used as the resin particles. If necessary, the resin particles may contain other additives in addition to the resin. Other additives include plasticizers, flame retardants, flame retardant aids, antistatic agents, spreading agents, cell control agents, fillers, coloring agents, weathering agents, anti-aging agents, antioxidants, and UV absorbers. , lubricants, antifogging agents, fragrances, and the like.

As the foaming agent with which the resin particles are impregnated, known volatile foaming agents and inorganic foaming agents can be used. Volatile foaming agents include aliphatic hydrocarbons such as propane, butane, and pentane, aromatic hydrocarbons, alicyclic hydrocarbons, and aliphatic alcohols. Examples of inorganic foaming agents include carbon dioxide gas, nitrogen gas, air, and inert gases (helium, argon, etc.). You may use together 2 or more types of these foaming agents. Among these foaming agents, inorganic foaming agents are preferred, and carbon dioxide gas is more preferred.
The content (impregnation amount) of the foaming agent is preferably 3 to 15 parts by weight with respect to 100 parts by weight of the polycarbonate resin. If the content of the foaming agent is less than 3 parts by weight, the foaming power will be low, and it may be difficult to foam well. If the content exceeds 15 parts by weight, the plasticizing effect is increased, shrinkage is likely to occur during foaming, the productivity is deteriorated, and it may be difficult to stably obtain the desired expansion ratio. A more preferable content of the foaming agent is 4 to 12 parts by weight.

As the impregnation method, there is a wet impregnation method in which resin particles are dispersed in an aqueous system and impregnated with a foaming agent while stirring. A dry impregnation method (vapor phase impregnation method), which does not generally use water, and the like can be mentioned. A dry impregnation method, which allows impregnation without using water, is particularly preferred. The impregnation pressure, impregnation time and impregnation temperature when the resin particles are impregnated with the foaming agent are not particularly limited.
The impregnation pressure is preferably 0.5 to 10 MPa (gauge pressure) from the viewpoint of efficient impregnation and obtaining better expanded beads and expanded molded articles. It is more preferably 1 to 4.5 MPa (gauge pressure).

The impregnation time is preferably 0.5 to 200 hours. If the time is less than 0.5 hours, the amount of impregnation of the foaming agent into the resin particles is reduced, and it may be difficult to obtain sufficient foaming power. If it is longer than 200 hours, productivity may decrease. A more preferable impregnation time is 1 to 100 hours.

The impregnation temperature is preferably 0 to 60°C. If the temperature is less than 0° C., the solubility of the foaming agent in the resin increases, and the foaming agent is impregnated more than necessary. Also, the diffusibility of the foaming agent in the resin is lowered. Therefore, it may be difficult to obtain sufficient foaming power (primary foaming power) within a desired period of time. When the temperature is higher than 60° C., the solubility of the foaming agent in the resin is lowered, and the impregnation amount of the foaming agent is lowered. Also, the diffusibility of the foaming agent in the resin increases. Therefore, it may be difficult to obtain sufficient foaming power (primary foaming power) within a desired period of time. A more preferred impregnation temperature is 5 to 50°C.

A surface treatment agent such as an anti-coupling agent (anti-coalescence agent), an anti-static agent, or a spreading agent may be added to the impregnated material.
The anti-bonding agent plays a role of preventing coalescence of foamed particles in the foaming process. Here, coalescence means that a plurality of foamed particles are united and integrated. Specific examples of the binding inhibitor include talc, calcium carbonate, aluminum hydroxide and the like.
Examples of the antistatic agent include polyoxyethylene alkylphenol ether and stearic acid monoglyceride.
Examples of the spreading agent include polybutene, polyethylene glycol, and silicone oil.

1-6-2. Production of Expanded Beads As a method for obtaining expanded beads (primary expanded beads) by expanding expandable beads, a method of heating and expanding expandable beads with hot air, a heat medium such as oil, steam (vapor) or the like is used. There is Steam is preferred for stable production.
It is preferable to use a sealed pressure-resistant foaming container for the foaming machine at the time of foaming. The steam pressure is preferably 0.10 to 0.80 MPa (gauge pressure), more preferably 0.25 to 0.45 MPa (gauge pressure). The foaming time may be any time required to obtain the desired foaming ratio. A preferred foaming time is 5 to 180 seconds. If the time exceeds 180 seconds, the expanded beads may start to shrink, and such expanded beads may not yield a foam molded product with good physical properties.
The anti-bonding agent may be removed prior to molding. As a removal method, it is preferable to wash with water or an acidic aqueous solution such as hydrochloric acid.

1-6-3. Adjustment of bulk multiple and average cell diameter By adjusting the impregnation conditions (impregnation pressure, impregnation time, impregnation temperature) and the primary foaming conditions (foaming pressure, foaming time) in the manufacturing process of the expanded beads, the bulk multiple and average cell diameter can be adjusted. The bubble diameter can be large or small.

2. Foam molded product The foam molded product uses a polycarbonate-based resin as a base resin. Also, the foamed molded product is composed of a plurality of foamed particles. Furthermore, the foamed molded product exhibits a value within the range of 2.5 to 12 μm/times when the average cell diameter of the foamed molded product is divided by the multiple of the foamed mold. The inventors have found that by adjusting the multiple and the average cell diameter, it is possible to provide a foam molded article with improved appearance and fusion bondability.

2-1. Value obtained by dividing the average cell diameter of the foam-molded product by the multiple of the foam-molded product . When the value is less than 2.5 μm/fold, the cell membrane becomes thin, and buckling of the cells causes contraction of the foamed particles, and as a result, the mechanical strength of the foam-molded product may decrease. If it is more than 12 μm/fold, the cell membrane becomes thicker and the moldability deteriorates, and as a result, the mechanical strength of the foam-molded product may deteriorate. The value is preferably 3.0 to 10.0 μm/times, more preferably 3.0 to 6.5 μm/times.

Preferably, the multiple is in the range of 2-20 times. When the multiple is less than 2 times, the foam film becomes thick, and the moldability may deteriorate and the adhesion between the foamed particles during molding may deteriorate. If it is more than 20 times, the cell membrane becomes thin and breaks during molding, and the ratio of open cells increases, which may lead to deterioration in the strength of the molded body. The multiple is more preferably 3 to 18 times, even more preferably 5 to 16 times.

2-2. Bubble Number Density The bubble number density X is calculated from the foamed particles forming the foamed molded product. The bubble number density is calculated by the following formula, as in the case of the foamed particles.
Bubble number density = (ρ/D−1)/{(4/3)·π·(C/10000/2) ³ }
can be calculated from Here, D is the density of the foam molded article.

The bubble number density X is preferably 1.0×10 ⁷ to 1.0×10 ⁹ /cm ³ . If the bubble number density is outside the above specific range, the moldability may be poor and the mechanical strength may be lowered. The preferred range and more preferred range for the cell number density are the same as the respective ranges for the expanded beads.
Furthermore, the preferred range, the reason for setting the range, the more preferred range, and the further preferred range of the average cell diameter C and the density ρ of the polycarbonate-based resin are the same as those of the expanded beads.
The density D of the foam molded product is preferably in the range of 12-600 kg/m ³ . If the density D is less than 12 kg/m ³ , the cell membrane becomes thin and breaks during molding, and the ratio of open cells increases, which may lead to deterioration in the strength of the molded body. If it is more than 600 kg/m ³ , the cell membrane may become thick, resulting in deterioration of moldability and adhesion between foamed grains during molding. Density D is more preferably 24 to 240 kg/m ³ , still more preferably 30 to 120 kg/m ³ .
The foam molded article preferably has an average cell wall thickness in the range of 1 to 15 μm. When the average cell wall thickness is less than 1 μm, moldability, particularly fusion bonding, may deteriorate during molding. If it is larger than 15 μm, it may become difficult to increase the magnification. More preferably, the average cell wall thickness is 1 to 10 μm, and even more preferably 1 to 5 μm.

2-3. Open-cell rate The open-cell rate is preferably 0 to 50%. If the open cell ratio is more than 50%, the mechanical strength may become poor. The open cell ratio is more preferably 0 to 40%, even more preferably 0 to 30%.

2-4. Polycarbonate-based resin As the polycarbonate-based resin, the same polycarbonate-based resin as that for the foamed particles can be used.
2-5. Use of foam molded article The foam molded article is not particularly limited, and can have various shapes depending on the application. For example, foam molded products are used in building materials (civil engineering, housing, etc.), parts of transportation equipment such as automobiles, aircraft, railroad vehicles, and ships, structural members such as windmills and helmets, packaging materials, and FRP cores as composite members. It can take various shapes depending on the application such as the material.
Automobile parts include, for example, parts used in the vicinity of the engine, exterior materials, and the like. Examples of automobile parts include floor panels, roofs, bonnets, fenders, undercovers, wheels, steering wheels, containers (casings), hood panels, suspension arms, bumpers, sun visors, trunk lids, luggage boxes, and seats. , doors and cowls.

2-6. Method for Producing Foamed Molded Article The foamed molded article can be obtained, for example, by imparting force to expand the air bubbles of the foamed particles, and then subjecting the foamed particles to a molding process.
It is preferable to impregnate the foamed particles with a foaming agent to impart a foaming power (secondary foaming power) before producing the foam molded article.
As the impregnation method, there is a wet impregnation method in which foamed particles are dispersed in a water system and impregnated with a foaming agent while stirring. A dry impregnation method (vapor phase impregnation method), which does not generally use water, and the like can be mentioned. A dry impregnation method, which allows impregnation without using water, is particularly preferred. The impregnation pressure, impregnation time and impregnation temperature when impregnating the expanded particles with the foaming agent are not particularly limited.

As the foaming agent to be used, the foaming agent at the time of manufacturing the expanded beads can be used. Among these, it is preferable to use an inorganic foaming agent. In particular, it is preferable to use one or a combination of two or more of nitrogen gas, air, inert gas (helium, argon), and carbon dioxide gas.
The pressure for applying the internal pressure is desirably a pressure that does not crush the foamed beads and is within a range that allows the application of foaming force. Such pressure is preferably 0.1 to 4 MPa (gauge pressure), more preferably 0.3 to 3 MPa (gauge pressure). Such impregnation of the foamed particles with the foaming agent is referred to as internal pressure application.

The impregnation time is preferably 0.5 to 200 hours. If the time is less than 0.5 hours, the amount of the foaming agent impregnated into the foamed particles is too small, and it may be difficult to obtain the secondary foaming force necessary for molding. If it is longer than 200 hours, productivity may decrease. A more preferable impregnation time is 1 to 100 hours.
The impregnation temperature is preferably 0 to 60°C. If the temperature is less than 0°C, it may be difficult to obtain sufficient secondary foaming power within the desired time. If the temperature is higher than 60°C, it may be difficult to obtain sufficient secondary foaming power within the desired time. A more preferred impregnation temperature is 5 to 50°C.

The foamed particles to which the internal pressure has been applied are removed from the impregnated container, supplied to the molding space formed in the molding die of the foam molding machine, and then a heating medium is introduced to enable in-mold molding into the desired foamed molded product. . The foam molding machine includes an EPS molding machine used to produce foamed articles from polystyrene-based resin expanded particles, and a high-pressure molding machine used to produce foamed articles from polypropylene-based resin expanded particles. A machine or the like can be used. As for the heating medium, since the foamed particles may shrink or have poor fusion when the heating time is long, a heating medium that can give high energy in a short time is desired. Steam is suitable as such a heating medium. be.
The steam pressure is preferably 0.2 to 1.0 MPa (gauge pressure). Also, the heating time is preferably 10 to 90 seconds, more preferably 20 to 80 seconds.
In addition, the adjustment of the multiple and the average cell diameter is carried out in addition to the use of expanded particles having the above-mentioned specific bulk multiple and average cell diameter. Pressure) and primary foaming conditions (foaming pressure, foaming time) can be adjusted to increase or decrease the multiple and average cell diameter.

2-7. Reinforced Composite A reinforced composite may be obtained by laminating and integrating a skin material on the surface of the foam molded body. When the foamed article is a foam sheet, it is not necessary to laminate and integrate on both sides of the foamed article, and it is sufficient that the skin material is laminated on at least one of the two surfaces of the expanded article. Lamination of the skin material may be determined according to the application of the reinforced composite. Above all, considering the surface hardness and mechanical strength of the reinforced composite, it is preferable that the skin material is laminated and integrated on both sides of the foam molded body in the thickness direction.
The skin material is not particularly limited, and examples thereof include fiber-reinforced plastics, metal sheets, synthetic resin films, and the like. Among these, fiber-reinforced plastics are preferred. A reinforced composite having a fiber-reinforced plastic as a skin material is called a fiber-reinforced composite.
Reinforcing fibers constituting fiber-reinforced plastics include inorganic fibers such as glass fiber, carbon fiber, silicon carbide fiber, alumina fiber, tyranno fiber, basalt fiber, and ceramics fiber; metal fibers such as stainless steel fiber and steel fiber; fibers, polyethylene fibers, organic fibers such as polyparaphenylenebenzoxazole (PBO) fibers; and boron fibers. Reinforcing fibers may be used singly or in combination of two or more. Among them, carbon fiber, glass fiber and aramid fiber are preferred, and carbon fiber is more preferred. These reinforcing fibers have excellent mechanical properties in spite of their light weight.

The reinforcing fibers are preferably used as a reinforcing fiber base processed into a desired shape. Examples of the reinforcing fiber base material include woven fabrics, knitted fabrics, non-woven fabrics using reinforcing fibers, and face materials obtained by binding (stitching) fiber bundles (strands) in which reinforcing fibers are aligned in one direction with threads. . Plain weave, twill weave, satin weave and the like can be used as the weaving method of the woven fabric. Examples of the thread include synthetic resin thread such as polyamide resin thread and polyester resin thread, and stitch thread such as glass fiber thread.
As the reinforcing fiber base material, a single reinforcing fiber base material may be used without being laminated, or a plurality of reinforcing fiber base materials may be laminated and used as a laminated reinforcing fiber base material. As a laminated reinforcing fiber base material in which a plurality of reinforcing fiber base materials are laminated, (1) a laminated reinforcing fiber base material obtained by preparing a plurality of reinforcing fiber base materials of only one type and laminating these reinforcing fiber base materials, ( 2) A laminated reinforcing fiber base material in which multiple types of reinforcing fiber base materials are prepared and these reinforcing fiber base materials are laminated, (3) Fiber bundles (strands) in which reinforcing fibers are aligned in one direction are bound with threads ( A plurality of reinforcing fiber base materials are prepared by sewing), and these reinforcing fiber base materials are superimposed so that the fiber directions of the fiber bundles are oriented in different directions, and the superimposed reinforcing fiber base materials are threaded. A laminated reinforcing fiber base material or the like that is integrated (stitched) with is used.

Fiber-reinforced plastics are made by impregnating reinforcing fibers with synthetic resin. The impregnated synthetic resin binds and integrates the reinforcing fibers.
The method for impregnating the reinforcing fibers with the synthetic resin is not particularly limited, and includes, for example, (1) a method of immersing the reinforcing fibers in a synthetic resin, and (2) a method of coating the reinforcing fibers with a synthetic resin.
As the synthetic resin with which the reinforcing fibers are impregnated, either a thermoplastic resin or a thermosetting resin can be used, and the thermosetting resin is preferably used. The thermosetting resin with which the reinforcing fibers are impregnated is not particularly limited, and may be epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin, maleimide. Examples thereof include resins obtained by prepolymerizing a resin and a cyanate ester resin. Epoxy resins and vinyl ester resins are preferred because of their excellent heat resistance, impact absorption, and chemical resistance. The thermosetting resin may contain additives such as curing agents and curing accelerators. In addition, a thermosetting resin may be used independently and 2 or more types may be used together.

The thermoplastic resin with which the reinforcing fibers are impregnated is not particularly limited, and examples thereof include olefin resins, polyester resins, thermoplastic epoxy resins, amide resins, thermoplastic polyurethane resins, sulfide resins, acrylic resins, and the like. Polyester-based resins and thermoplastic epoxy resins are preferred because they are excellent in adhesiveness with foam molded articles or adhesiveness between reinforcing fibers constituting fiber-reinforced plastics. The thermoplastic resin may be used alone or in combination of two or more.
The thermoplastic epoxy resin may be a polymer or copolymer of epoxy compounds having a linear structure, or a copolymer of an epoxy compound and a monomer capable of polymerizing with the epoxy compound. and a copolymer having a linear structure. Specifically, thermoplastic epoxy resins include, for example, bisphenol A type epoxy resin, bisphenol fluorene type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, cycloaliphatic type epoxy resin, and long-chain aliphatic type epoxy resin. Epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins and the like can be mentioned, and bisphenol A type epoxy resins and bisphenol fluorene type epoxy resins are preferred. The thermoplastic epoxy resins may be used alone, or two or more of them may be used in combination.

Thermoplastic polyurethane resins include polymers having a linear structure obtained by polymerizing diols and diisocyanates. Diols include, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol and the like. The diols may be used alone or in combination of two or more. Diisocyanates include, for example, aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates. Diisocyanate may be used alone or in combination of two or more. The thermoplastic polyurethane resin may be used alone or in combination of two or more.
The content of the synthetic resin in the fiber-reinforced plastic is preferably 20-70% by weight. If the content is less than 20% by weight, the binding between the reinforcing fibers and the adhesion between the fiber-reinforced plastic and the foam molded product will be insufficient, and the mechanical properties of the fiber-reinforced plastic and the mechanical strength of the fiber-reinforced composite will be insufficient. may not be sufficiently improved. If it is more than 70% by weight, the mechanical properties of the fiber-reinforced plastic may deteriorate, and the mechanical strength of the fiber-reinforced composite may not be sufficiently improved. More preferably, the content is 30 to 60% by weight.
The thickness of the fiber-reinforced plastic is preferably 0.02-2 mm, more preferably 0.05-1 mm. A fiber-reinforced plastic having a thickness within this range has excellent mechanical properties in spite of being lightweight.
The basis weight of the fiber-reinforced plastic is preferably 50-4000 g/m ² , more preferably 100-1000 g/m ² . A fiber-reinforced plastic having a basis weight within this range has excellent mechanical properties in spite of being lightweight.

Next, a method for manufacturing a reinforced composite will be described. The method for manufacturing a reinforced composite by laminating and integrating the skin material on the surface of the foam molded body is not particularly limited. (2) Laminating a fiber-reinforced plastic forming material in which reinforcing fibers are impregnated with a thermoplastic resin on the surface of the foam molded product, and using the thermoplastic resin impregnated in the reinforcing fibers as a binder to form a foam molded product. (3) Laminating a fiber-reinforced plastic forming material, in which reinforcing fibers are impregnated with an uncured thermosetting resin, on the surface of the foam molded body. Then, a method of laminating and integrating a fiber-reinforced plastic formed by curing the thermosetting resin using a thermosetting resin impregnated in the reinforcing fiber as a binder on the surface of the foam molded body, (4) Foam molded body A heated and softened skin material is provided on the surface of the foam molding, and the skin material is pressed against the surface of the foam molded body, thereby deforming the skin material along the surface of the foam molded body as necessary. Examples include a method of lamination and integration on the surface of the body, (5) a method generally applied in molding of fiber-reinforced plastics, and the like. The above method (4) can also be suitably used from the viewpoint that the foam molded article has excellent mechanical properties such as load resistance in a high-temperature environment.
Methods used in molding fiber-reinforced plastics include, for example, an autoclave method, a hand lay-up method, a spray-up method, a PCM (Prepreg Compression Molding) method, an RTM (Resin Transfer Molding) method, and a VaRTM (Vacuum assisted Resin Transfer Molding) method. law, etc.

The fiber-reinforced composite thus obtained is excellent in heat resistance, mechanical strength and lightness. Therefore, it can be used in a wide range of applications, such as the field of transportation equipment such as automobiles, aircraft, railroad cars, and ships, the field of home appliances, the field of information terminals, and the field of furniture.
For example, fiber reinforced composites are used for parts of transportation equipment, parts for transportation equipment including structural parts constituting the main body of transportation equipment (especially automobile parts), wind turbine wings, robot arms, cushioning materials for helmets, It can be suitably used as a transportation container such as an agricultural product box, a heat and cold insulation container, and a packing material for rotor blades and parts of industrial helicopters.
According to the present invention, there is provided an automobile part composed of the fiber-reinforced composite of the invention, such as a floor panel, roof, bonnet, fender, undercover, wheel, steering wheel, Examples include parts such as containers (casings), hood panels, suspension arms, bumpers, sun visors, trunk lids, luggage boxes, seats, doors, and cowls.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. First, methods for measuring various physical properties in Examples are described below.
[Density of polycarbonate resin]
The density of the polycarbonate-based resin was measured by the method specified in ISO1183-1:2004 or ASTM D-792.

[Blowing agent impregnation amount]
The foaming agent impregnation amount was a value calculated by the following formula.
Foaming agent impregnated amount (% by weight) = (weight immediately after impregnation and removal - weight before impregnation) / weight before impregnation x 100

[Average particle size]
The average particle size was a value expressed by D50.
Specifically, using a low tap type sieve shaker (manufactured by Iida Seisakusho Co., Ltd.), sieve openings of 26.5 mm, 22.4 mm, 19.0 mm, 16.0 mm, 13.2 mm, 11.20 mm, 9.5 mm, 22.4 mm, 19.0 mm, 16.0 mm, 13.2 mm, 11.20 mm. 50mm, 8.80mm, 6.70mm, 5.66mm, 4.76mm, 4.00mm, 3.35mm, 2.80mm, 2.36mm, 2.00mm, 1.70mm, 1.40mm, 1.18mm, JIS standard sieves (JIS Z8801 -1: 2006), about 25 g of the sample was classified for 10 minutes, and the weight of the sample on the sieve was measured. A cumulative weight distribution curve was created from the obtained results, and the particle size (median size) at which the cumulative weight was 50% was defined as the average particle size.

[Average cell diameter of expanded particles]
The central part of the cross section obtained by extracting the expanded beads obtained by the primary expansion and dividing the expanded beads into two at the central part was photographed by using a scanning electron microscope at a magnification of 200 to 1200 times. The captured image was printed on A4 paper. Draw three arbitrary straight lines (length 60 mm) parallel to the vertical and horizontal directions on the cross-sectional image of the expanded bead. I drew three lines in each direction.
It should be noted that, as much as possible, an arbitrary straight line should not come in contact with a bubble only at the point of contact, and if it does, this bubble is also added to the number. The number of bubbles counted for three arbitrary straight lines in each of the vertical and horizontal directions was arithmetically averaged to obtain the number of bubbles.
The average chord length t of bubbles was calculated by the following equation from the image magnification for counting the number of bubbles and the number of bubbles.
Average chord length t (mm) = 60/(number of bubbles x image magnification)
The image magnification was obtained by measuring the scale bar on the image to 1/100 mm using "Digimatic Caliper" manufactured by Mitutoyo Co., Ltd. and using the following formula.
Image magnification = measured value of scale bar (mm) / displayed value of scale bar (mm)
Then, the bubble diameter was calculated by the following formula.
Average bubble diameter C (μm) = (t/0.616) × 1000

[Average cell diameter of foam molded product]
A 50 mm long, 50 mm wide, and 30 mm thick piece is cut out from the center of a molded body measuring 400 mm long, 300 mm wide, and 30 mm thick. and took the picture. The captured image was printed on A4 paper. Draw three arbitrary straight lines (length 60 mm) parallel to the vertical and horizontal directions on the cross-sectional image of the foam molding, and if there are bubbles with extremely large diameters, avoid the bubbles and draw an arbitrary straight line Three lines were drawn in each direction.
It should be noted that, as much as possible, an arbitrary straight line should not come in contact with a bubble only at the point of contact, and if it does, this bubble is also added to the number. The number of bubbles counted for three arbitrary straight lines in each of the vertical and horizontal directions was arithmetically averaged to obtain the number of bubbles.
The average chord length t of bubbles was calculated by the following equation from the image magnification for counting the number of bubbles and the number of bubbles.
Average chord length t (mm) = 60/(number of bubbles x image magnification)
The image magnification was obtained by measuring the scale bar on the image to 1/100 mm using "Digimatic Caliper" manufactured by Mitutoyo Co., Ltd. and using the following formula.
Image magnification = measured value of scale bar (mm) / displayed value of scale bar (mm)
Then, the average bubble diameter was calculated by the following formula.
Average bubble diameter C (μm) = (t/0.616) × 1000

[Bulk Density and Bulk Multiple of Expanded Particles]
Approximately 1000 cm ³ of expanded particles were filled into a graduated cylinder to the 1000 cm ³ mark. When the measuring cylinder was viewed horizontally and even one expanded particle reached the scale of 1000 cm ³ , filling of the expanded particles into the graduated cylinder was completed at that point. Next, the weight of the foamed particles filled in the graduated cylinder was weighed to two significant figures after the decimal point, and the weight was taken as Wg. Then, the bulk density of the expanded particles was determined by the following formula.
Bulk density (kg/m ³ )=(W/1000)/[1000×(0.01) ³ ]
The bulk multiple was a value obtained by multiplying the reciprocal of the bulk density by the density (kg/m ³ ) of the polycarbonate-based resin.

[Apparent Density of Expanded Beads]
The weight A (g) of about 25 cm ³ of foamed particles was measured. Subsequently, an empty wire mesh container in which the foamed particles contained in the container with the lid closed was not spilled was immersed in water, and the weight B (g) of the empty wire mesh container in the state of being immersed in water was measured. Next, after putting the entire amount of the foamed particles in the wire mesh container, the wire mesh container is immersed in water, and the container is shaken several times to remove air bubbles attached to the container and the foamed particles. The total weight C (g) of the wire mesh container immersed in water and the total amount of foamed particles placed in the wire mesh container was measured. Then, the apparent density D (kg/m ³ ) of the expanded beads was calculated by the following formula.
D=A/(A+(B−C))×1000
The apparent multiple was obtained by multiplying the reciprocal of the apparent density by the density (kg/m ³ ) of the polycarbonate resin.

[Density and multiple of foam molded product]
The weight (a) and volume (b) of a test piece (example 75 x 300 x 30 mm) cut from a foamed molded product (dried at 40°C for 20 hours or more after molding) are each at least three significant figures. Then, the density (kg/m ³ ) of the foam molded product was determined by the formula (a)/(b).
The multiple was obtained by multiplying the reciprocal of the density by the density (kg/m ³ ) of the polycarbonate resin.

[Open cell ratio of foamed particles]
A sample cup of "air comparison type hydrometer 1000 type" manufactured by Tokyo Science Co., Ltd. was prepared, and the total weight A (g) of the foamed particles was measured to fill about 80% of the sample cup. The volume B (cm ³ ) of the entire foamed beads was measured by a 1-1/2-1 atmospheric pressure method using an air comparison type hydrometer, and measured with a standard sphere (large 28.96 cm ³ small 8.58 cm ³ ). Corrected. Subsequently, an empty wire mesh container in which the expanded particles would not spill, which was put in with the lid closed, was immersed in water, and the weight C (g) of the empty wire mesh container in the state of being immersed in water was measured. Next, after putting the entire amount of the foamed particles in the wire mesh container, the wire mesh container is immersed in water, and the container is shaken several times to remove air bubbles attached to the container and the foamed particles. A total weight D (g) of the wire mesh container immersed in water and the total amount of foamed particles placed in the wire mesh container was measured. Then, the apparent volume E (cm ³ ) of the expanded beads was calculated by the following formula. Based on this apparent volume E (cm ³ ) and the volume B (cm ³ ) of the entire expanded beads, the open cell ratio of the expanded beads was calculated by the following formula.
E = A + (CD)
Open cell rate (%) = 100 × (EB) / E

[Continuous cell ratio of foam molded product]
The foam is cut out so that all six sides of the molded body do not have a molded surface skin, and the cut surface is finished with a "FK-4N" bread slicer manufactured by Fujishima Koki Co., Ltd., and a cubic shape of 25 mm × 25 mm × 25 mm is tested. Five pieces were made. The outer dimensions of the obtained test piece were measured to 1/100 mm using Mitutoyo's "Digimatic Caliper" vernier caliper, and the apparent volume (cm ³ ) was determined. Next, the volume (cm ³ ) of the test piece was determined by the 1-1/2-1 atmospheric pressure method using a "1000 type" air comparison type hydrometer manufactured by Tokyo Science Co., Ltd. The open-cell ratio (%) was calculated by the following formula, and the average value of the open-cell ratios of five test pieces was obtained. The test piece was previously stored for 16 hours under a JIS K7100:1999 symbol 23/50, grade 2 environment, and then measured under the same environment. The air comparison type hydrometer was corrected with a standard ball (large 28.96 cm ³ small 8.58 cm ³ ).
Open cell ratio (%) = (Apparent volume - Volume measured by air comparison type hydrometer) / Apparent volume x 100

[Average Cell Wall Thickness of Expanded Beads]
The average cell wall thickness of the expanded beads was calculated as follows. It was calculated from the following formula using the average cell diameter and apparent multiple of the expanded beads obtained by the above measuring method.
Average bubble wall thickness (μm)=average bubble diameter C (μm)×(1/(1−(1/apparent multiple)) ^(1/3) −1)

[Average Cell Wall Thickness of Foam Mold]
The average cell wall thickness of the foam molded product was calculated as follows. It was calculated from the following formula using the average cell diameter and multiple of the foamed molded product obtained by the above measuring method.
Average cell wall thickness (μm)=average cell diameter C (μm)×(1/(1−(1/multiple)) ^(1/3) −1)

[Bending Test: Density and Maximum Point Load, Stress, Displacement and Energy]
The load, stress, displacement and energy at the maximum point were measured according to JIS K7221-1:2006 "Rigid Foamed Plastic-Bending Test-Part 1: Determination of Flexibility". That is, a rectangular parallelepiped test piece having a width of 25 mm, a length of 130 mm, and a thickness of 20 mm was cut out from the foam molded product. For the measurement, a Tensilon universal testing machine ("UCT-10T" manufactured by Orientec) was used. The bending maximum point stress of bending strength was calculated using a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Soft Brain Co.).
A strip-shaped test piece was placed on a support stand, and the bending maximum point stress was measured under the conditions of a load cell of 1000 N, a test speed of 10 mm/min, a tip jig of the support stand of 5R, and an opening width of 100 mm. The number of test pieces is 5 or more, and the symbol "23/50" of JIS K 7100: 1999 (temperature 23 ° C, relative humidity 50%), after conditioning for 16 hours in a standard atmosphere of class 2, the same Measured under standard atmosphere. The arithmetic mean value of the maximum bending point stress of each test piece was taken as the maximum bending point stress of the foam molded product.
The maximum bending point stress per unit density was calculated by dividing the maximum bending point stress by the density of the foam molded article.
The density (kg/m ³ ) of the foamed molded product was obtained by measuring the weight (a) and volume (b) of a test piece cut out from the foamed molded product and using the formula (a)/(b).

[Bending test: elastic modulus]
The flexural modulus was measured by a method conforming to JIS K7221-1:2006 "Rigid Foamed Plastic-Bending Test-Part 1: Determination of Flexibility". That is, a rectangular parallelepiped test piece having a width of 25 mm, a length of 130 mm, and a thickness of 20 mm was cut out from the foam molded product. For the measurement, a Tensilon universal testing machine ("UCT-10T" manufactured by Orientec) was used. The flexural modulus was calculated by the following formula using a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Soft Brain Co.). The number of test pieces is 5 or more, and the symbol "23/50" of JIS K 7100: 1999 (temperature 23 ° C, relative humidity 50%), after conditioning for 16 hours in a standard atmosphere of class 2, the same Measured under standard atmosphere. The arithmetic average value of the compression modulus of each test piece was taken as the flexural modulus of the foam molded product.
The flexural modulus was calculated by the following equation using the initial linear portion of the load-deformation curve.
E = Δσ/Δε
E: Flexural modulus (MPa)
Δσ: stress difference between two points on a straight line (MPa)
Δε: difference in deformation between the same two points (%)
Also, the bending elastic modulus per unit density was calculated by dividing the bending elastic modulus by the density of the foam molded product.

[Compression Test: Density and 5%, 10%, 25% and 50% Stress]
The 5% compressive stress, 10% compressive stress, 25% compressive stress, and 50% compressive stress of the foam molded product were measured according to the method described in JIS K7220:2006 "Rigid Foamed Plastics - Determination of Compressive Properties". That is, using a Tensilon universal testing machine ("UCT-10T" manufactured by Orientec Co., Ltd.) and a universal testing machine data processing system ("UTPS-237S Ver, 1.00" manufactured by Soft Brain Co., Ltd.), a specimen size cross section of 50 mm The compressive strength (5% deformed compressive stress, 25% deformed compressive stress, compressive elastic modulus) was measured at a compression speed of 2.5 mm/min at a thickness of 25 mm and 50 mm. The number of test pieces is 5 or more, and the symbol "23/50" of JIS K 7100: 1999 (temperature 23 ° C, relative humidity 50%), after conditioning for 16 hours in a standard atmosphere of class 2, the same Measurements were performed under standard atmosphere. The arithmetic average values of the compressive strength of each test piece (5% deformation compression stress, 10% deformation compression stress, 25% deformation compression stress, 50% deformation compression stress) are respectively 5% compression stress, 10 % compressive stress, 25% compressive stress, and 50% compressive stress.
(5% (10%, 25%, 50%) deformation compressive stress)
5% (10%, 25%, 50%) deformation compressive stress was calculated by the following equation. The values in parentheses are the conditions for calculating the 10% deformation compressive stress, the 25% deformation compressive stress, and the 50% deformation compressive stress.
σ5(10,25,50)=F5(10,25,50)/ _A0
σ5 (10, 25, 50): 5% (10%, 25%, 50%) deformation compressive stress (MPa)
F5 (10, 25, 50): Force (N) at 5% (10%, 25%, 50%) deformation
A ₀ : Initial cross-sectional area of test piece (mm ² )

[Compression test: elastic modulus]
The compression elastic modulus of the foam molded product was measured by the method described in JIS K7220:2006 "Rigid foamed plastics - Determination of compression properties". That is, using a Tensilon universal testing machine ("UCT-10T" manufactured by Orientec Co., Ltd.) and a universal testing machine data processing system ("UTPS-237S Ver, 1.00" manufactured by Soft Brain Co., Ltd.), a specimen size cross section of 50 mm The compressive elastic modulus was calculated by the following formula with a thickness of 25 mm and a compression speed of 2.5 mm/min. The number of test pieces is 5 or more, and the symbol "23/50" of JIS K 7100: 1999 (temperature 23 ° C, relative humidity 50%), after conditioning for 16 hours in a standard atmosphere of class 2, the same Measurements were performed under standard atmosphere. The arithmetic mean value of the compression modulus of each test piece was taken as the compression modulus of the foam molded article.
Compressive modulus was calculated by the following equation using the initial linear portion of the load-deformation curve.
E = Δσ/Δε
E: compression modulus (MPa)
Δσ: stress difference between two points on a straight line (MPa)
Δε: difference in deformation between the same two points (%)
Also, the compression modulus per unit density was calculated by dividing the compression modulus by the density of the foam molded product.

Example 1
(Resin particle manufacturing process)
Polycarbonate resin particles (PANLITE manufactured by Teijin Limited, L-1250Y, density 1.20×10 ³ kg/m ³ ) were dried at 120° C. for 4 hours. The obtained dried product was supplied to a single-screw extruder with a diameter of 40 mm at a rate of 10 kg/hr and melt-kneaded at 290°C. Subsequently, cooling water of about 10 ° C. is supplied from the die hole (four nozzles with a diameter of 1.5 mm are arranged) of the die (temperature: 290 ° C., inlet side resin pressure: 13 MPa) attached to the tip of the single screw extruder. It is extruded into the chamber containing the resin, and the rotating shaft of a rotary blade having four cutting blades is rotated at a rotation speed of 5000 rpm to cut into granules. 4 mm) were produced.
(Impregnation process)
After 100 parts by weight of the resin particles were sealed in a pressure vessel, and the inside of the pressure vessel was replaced with carbon dioxide gas, carbon dioxide gas was pressurized to an impregnation pressure of 2.0 MPa. After standing in an environment of 20° C. and 24 hours of impregnation time, the pressure inside the pressure vessel was slowly released over 5 minutes. In this manner, the resin particles were impregnated with carbon dioxide to obtain expandable particles. The impregnation amount of the foaming agent at this time was 5.8% by weight.

(foaming process)
Immediately after depressurization in the impregnation step, the expandable particles are taken out from the pressure vessel, and the impregnated material is foamed with steam in a high-pressure foaming tank while stirring at a foaming temperature of 142 ° C. for 39 seconds using steam. let me After foaming, drying was performed using a flash dryer to obtain foamed particles. The bulk density of the obtained foamed particles was measured by the method described above and found to be 109 kg/m ³ (bulk multiple: 11.05 times).
(Molding process)
After leaving the obtained expanded beads at room temperature (23° C.) for 1 day, they were sealed in a pressure vessel, and after replacing the inside of the pressure vessel with nitrogen gas, the nitrogen gas was increased to an impregnation pressure (gauge pressure) of 1.0 MPa. pressed in. It was left to stand in an environment of 20° C. and subjected to pressure curing for 24 hours. After taking out, fill a molding die of 30 mm × 300 mm × 400 mm, heat with steam of 0.85 MPa for 40 seconds, and then cool until the maximum surface pressure of the foamed molded product is reduced to 0.05 MPa. to obtain a foam molded product with a multiple of 11.45 (density: 105 kg/m ³ ).

Example 2
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 1.7 MPa
Foaming agent impregnation amount: 5.6% by weight
Foaming time: 42 seconds Example 3
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 1.5 MPa
Foaming agent impregnation amount: 5.0% by weight
Foaming time: 48 seconds

Example 4
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 1.3 MPa
Foaming agent impregnation amount: 4.5% by weight
Foaming time: 61 seconds Example 5
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 2.0 MPa
Foaming agent impregnation amount: 5.8% by weight
Foaming temperature: 144°C
Foaming time: 22 seconds

Example 6
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 2.0 MPa
Foaming agent impregnation amount: 5.6% by weight
Foaming time: 8 seconds Example 7
Expanded beads were obtained in the same manner as in Example 1 except for the following conditions.
Polycarbonate resin particles: Teijin Panlite Z-2601 (density: 1.2×10 ³ kg/m ³ )
Impregnation pressure: 2.0 MPa
Foaming agent impregnation amount: 5.3% by weight
Foaming temperature: 144°C
Foaming time: 21 seconds A foamed molded product was obtained in the same manner as in Example 1, except that nitrogen gas was pressurized to an impregnation pressure (gauge pressure) of 1.6 MPa in the molding step.

Example 8
Expanded beads were obtained in the same manner as in Example 1 except for the following conditions.
Polycarbonate resin particles: Teijin Panlite K-1300Y (density: 1.2×10 ³ kg/m ³ )
Impregnation pressure: 2.0 MPa
Foaming agent impregnation amount: 5.5% by weight
Foaming temperature: 148°C
Foaming time: 26 seconds A foamed molded article was obtained in the same manner as in Example 1, except that nitrogen gas was pressurized to an impregnation pressure (gauge pressure) of 1.6 MPa in the molding step.
Example 9
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Polycarbonate resin particles: Wonderlight PC-110 manufactured by Chibi Jitsugyo Co., Ltd. (density: 1.2×10 ³ kg/m ³ )
Impregnation pressure: 2.0 MPa
Foaming agent impregnation amount: 5.8% by weight
Foaming temperature: 139°C
Foaming time: 41 seconds

Comparative example 1
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 4.0 MPa
Foaming agent impregnation amount: 9.5% by weight
Foaming time: 8 seconds Comparative Example 2
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Polycarbonate resin particles: Lexan 153 manufactured by Savik (density: 1.2×10 ³ kg/m ³ )
Impregnation pressure: 4.0 MPa
Foaming agent impregnation amount: 9.9% by weight
Foaming time: 10 seconds

Comparative example 3
Expanded beads and an expanded molded article were obtained in the same manner as in Example 1 except for the following conditions.
Impregnation pressure: 1.0 MPa
Foaming agent impregnation amount: 3.5% by weight
Foaming time: 147 seconds

Tables 1 to 4 show various physical properties of the expanded beads and expanded molded articles of Examples and Comparative Examples.
1 to 3 show enlarged photographs of the cut surfaces of the foamed particles and the foamed moldings of Examples and Comparative Examples.

From Tables 1 to 4 above, it can be seen that a foam molded article having high mechanical strength can be obtained by setting the bulk multiple and the average cell diameter within specific ranges.
In addition, from FIGS. 1 to 3, the foamed molded article of the comparative example has insufficient fusion between the expanded particles and many gaps exist between the expanded particles, so the external appearance is poor. It can be seen that the foamed molded article of the example has almost no gaps between the foamed particles and has a good appearance.

Claims (5)

Expanded particles having an aromatic polycarbonate-based resin as a base resin,
When the average cell diameter of the expanded beads is divided by the bulk multiple of the expanded beads, the expanded beads have a value within the range of 3.0 to 12 μm/times and an open cell rate of 0 to 10%. Foamed particles characterized by: 2. The expanded bead according to claim 1, wherein the expanded bead exhibits a cell number density of 1.0×10 ⁷ to 1.0×10 ⁹ cells/cm ³ . 3. The expanded beads according to claim 1, wherein the expanded beads have a bulk multiple of 2 to 20 times. A foamed molded article composed of a plurality of foamed particles with an aromatic polycarbonate resin as a base resin,
When the average cell diameter of the foamed molded body is divided by the multiple of the foamed molded body, the foamed molded body has a value within the range of 3.0 to 12 μm/times , and an open cell rate of 0 to 40%. A foam molded article characterized by having 5. The foamed molded article according to claim 4, which is obtained by in-mold expansion of the expanded particles according to any one of claims 1 to 3 .

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